1. Field of the Invention
The present invention relates to a device for mounting and demounting an optical element, and more specifically, for inserting an optical element into an optical lens system, such as an image forming lens system of, in particular, a broadcasting television camera and removing the same from the optical lens system.
2. Description of Related Art
It is required so often for broadcasting television cameras such as electronic news gathering cameras (ENG cameras) to provide magnified images. An image forming lens system, namely a taking lens system, for such an ENG camera is provided with an optical element switch device for inserting an optical element such as a converter or extender lens into an optical path of the taking lens system for altering the focal length of the taking lens system and removing the optical element from the taking lens system. One of extender switching devices that is disclosed in, for example, Japanese Unexamined Patent Publication No. 9-171135 includes first and second extenders pivotally mounted on a common pivot shaft so as to be moves between a working position and rest positions independently through operation of a manual operation lever. The extender switching device is provided with urging means such as a tension spring for retaining an extender lens in a stationary state in a predetermined position and a damper mechanism for preventing generation of hitting sound and/or vibrations when the extender lens is moved from the rest position to the working position or vice versa.
However, the extender switching device disclosed in the publication needs a number of constituent parts for the retainer spring and the damper mechanism and increases the number of man-hour for fabrication in consequence.